Bring a large pot of salted water to a boil. Meanwhile, shell the favas and discard the pods. Boil the favas for 4 minutes, strain then immediately plunge into ice water. Let cool for 2 minutes then pierce the favas and squeeze them out of their skins. Separate ¾ of the favas and puree in a food processor.

In a separate large saucepan bring the broth to a simmer and keep it hot. Meanwhile, in another large saucepan over medium heat, melt 1 ½ tablespoons of the butter and add the onions. Reduce the heat to low and cook for about 5 minutes; do not brown the onions. Add the rice and cook, while stirring, for 2 minutes. Add the wine, increase the heat to medium, and stir constantly. When the wine has been absorbed, add a little of the stock. Once the stock is absorbed, add a little more. Repeat this process, stirring constantly, until the rice is cooked through.

To the cooked rice add the pureed favas, the remaining 1 ½ tablespoons of butter, the rest of the favas, and the cheese. Cook over medium heat, stirring, until the butter and cheese melt and the puree is incorporated evenly. Season with salt.